Method for fetching a target bin stored in a storage system

ABSTRACT

A method for fetching a target bin stored in a storage system, wherein the storage system includes a three-dimensional storage grid containing a plurality of bins stacked in vertical stacks, supporting rails on the grid structure, and a plurality of vehicles, controllably arranged to move individually on the supporting rails. The method is performed by a control device in the system and comprises controlling at least one non-target vehicle to operate as intermediate storage for a bin located vertically above the target bin; controlling a target vehicle to pick up the target bin, and controlling the at least one non-target vehicle and the target vehicle to be positioned adjacent to each other in a linear manner on the supporting rails. A corresponding storage system has also been disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation under 35 U.S.C. § 120 of U.S.application Ser. No. 15/757,577 filed 3 May 2018, which a US NationalStage of international application PCT/EP2016/070476 filed 31 Aug. 2016.

FIELD OF THE INVENTION

The present invention relates to the field of controlled storage systemsand methods. More specifically, the invention relates to a method forfetching a target bin stored in a storage system and a storage systemwhich includes a control device operating in accordance with the method.

BACKGROUND

A prior art storage structure and a prior art vehicle for use with thestorage structure is illustrated in FIGS. 1 and 2, respectively. Thestorage structure 3 comprises a vehicle or robot 1 which is arranged tomove on dedicated supporting rails 13 and to receive a storage bin 2from a storage column 8 within a bin storage grid 15. The storagestructure 3 includes a plurality of such vehicles 1 and a dedicated binlift device 50, the latter being arranged to receive a storage bin 2from the vehicle 1 at the top level of the bin storing grid 15 and toconvey the storage bin 2 down in a vertical direction to a deliverystation 60.

When a particular storage bin (denoted a “target bin”) on a lower levelwithin the storage structure is to be fetched, a vehicle 1 is controlledto pick up the upper bin from the stack of bins located vertically abovethe target bin, and then the vehicle 1 is controlled to unload and storethis bin on a selected location on the upper level of the storage grid.This process may then be repeated until the target bin has become theupper bin in the vertical stack of bins. Then the target bin is fetchedby the vehicle 1 and carried by the vehicle 1 to the bin lift device 50.

This system and operational method has certain disadvantages. First, theintermediate storage of bins on top of the upper level of the storagegrid occupies area, resulting in obstructions for other vehicles thatare intended to move as freely as possible on the top of the upper levelof the storage grid. Second, a substantial amount of time is spent onthe loading and unloading of bins associated with the intermediatestorage. This in turn contributes to significant delays in the overallpick up time used to obtain a desired target bin.

WO-2013/167907 relates to a storage system suitable for storing multipleproduct lines in an automated warehouse environment. A first handlingdevice is capable of lifting a plurality of containers from a stack in asingle operation, and a second handling device is capable of lifting asingle container and moving the container laterally.

This system has certain disadvantages. Firstly, the first handlingdevice, which lifts a plurality of containers, causes a potentially tallstack of containers to be stored in the first handling device. Thisresults in instability and risk for overturning, in particularly duringacceleration/movement of the first handling device. Secondly, a specialmulti-bin handling device is needed for the lifting of a plurality ofcontainers. The multi-bin handling device is different from thesingle-bin handling device used to retain the single container. The useof dedicated handling devices for various purposes results in a complexsystem.

An object of the present invention is to solve, or at leastsubstantially alleviate, the above-described disadvantages of the priorart storage structures and methods.

SUMMARY

The invention has been set forth in the independent claims 1 and 6.

In an aspect, the invention provides a method for fetching a target binstored in a storage system, wherein the storage system includes athree-dimensional storage grid containing a plurality of bins stacked invertical stacks, supporting rails on the grid structure, and a pluralityof vehicles, controllably arranged to move individually on thesupporting rails, the method comprising:

-   -   controlling at least one non-target vehicle to operate as        intermediate storage for a bin located vertically above the        target bin;    -   controlling a target vehicle to pick up the target bin, and    -   controlling the at least one non-target vehicle and the target        vehicle to be positioned adjacent to each other in a linear        manner on the supporting rails.

In another aspect, the invention provides a storage system, including athree-dimensional storage grid containing a plurality of bins stacked invertical stacks; supporting rails on the grid structure; and a pluralityof vehicles, controllably arranged to move on the supporting rails, anda control device, wherein the control device is configured to enablefetching of a target bin stored in the storage system by

-   -   controlling at least one non-target vehicle to operate as        intermediate storage for a bin located vertically above the        target bin;    -   controlling a target vehicle to pick up the target bin; and    -   controlling the at least one non-target vehicle and the target        vehicle to be positioned adjacent to each other in a linear        manner on the supporting rails.

Advantageous additional features are set forth in the dependent claims.

The invention provides, i.a., the advantage that the area on top of theupper level of the storage grid will not be blocked by stationaryobstructions during retrieval of a desired target bin at a lower levelin the storage structure. Hence, other vehicles are allowed to move morefreely on the top of the upper level of the storage grid. Althoughnon-target vehicles that serve as intermediate storage for a bin alsotake up area on the top of the storage grid, the non-target vehicles maybe easily moved if necessary.

Another advantage of the invention is that the time spent on loading andunloading of bins that must be intermediately stored, will besubstantially reduced, compared with the methods and systems of thebackground art. Hence, the invention increases the overall retrievalspeed when fetching a desired target bin in the storage structure.

In particular, the feature of controlling the at least one non-targetvehicle and the target vehicle to be positioned adjacent to each otherin a linear manner on the supporting rails, results in substantiallyimproved retrieval speed when fetching a desired target bin in thestorage structure.

Another advantage of the invention is that only one type of vehicle isneeded. The one type of vehicle may serve as a target vehicle or anon-target vehicle, depending on its current mode of operation.

These and other characteristics of the invention will be clear from thefollowing description of an exemplary embodiment, given as anon-restrictive example, with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art storage structure;

FIG. 2 is a sectional view of a prior art robot or vehicle forming partof a storage structure as illustrated in FIG. 1;

FIG. 3 is a schematic flow chart illustrating a method for fetching atarget bin stored in a storage system.

FIG. 4 is a schematic block diagram illustrating a storage system.

FIG. 5-9 are schematic diagrams illustrating an exemplary operation ofthe method and system.

DETAILED DESCRIPTION

FIG. 1 and FIG. 2 have already been described above with reference tothe section background of the invention.

FIG. 3 is a schematic flow chart illustrating a method for fetching atarget bin stored in a storage system. The storage system includes athree-dimensional storage grid containing a plurality of bins stacked invertical stacks, supporting rails on the grid structure, and a pluralityof vehicles, controllably arranged to move on the supporting rails.

The method starts at the initiating step 300.

First, the non-target vehicle control step 310 is performed. Thenon-target vehicle control step 310 includes controlling at least onenon-target vehicle to operate as intermediate storage for at least onebin located vertically above the target bin.

As illustrated, the non-target vehicle control step 310 may includeseveral substeps, in order to obtain its task of controlling at leastone non-target vehicle to operate as intermediate storage for at leastone bin located vertically above the target bin. While otheralternatives are also possible, the non-target vehicle control step 310may, by example, include the following:

-   -   a first controlling sub step 320 of controlling the non-target        vehicle to move to a target location above the target bin;    -   a second controlling substep 330 of controlling the non-target        vehicle to pick up a bin from the vertical stack at the target        location;    -   a third controlling substep 340 of controlling the non-target        vehicle to rest at a neighbour location; and    -   a determination step 350 of determining if the target bin has        become the upper bin in the vertical stack at the target        location, and if this is not true, repeating the first 320,        second 330 and third 340 controlling steps.

Next, the target vehicle control step 360 is performed. The targetvehicle control step 360 includes controlling the target vehicle to pickup the target bin at the target location.

During the above process, the at least one non-target vehicle and thetarget vehicle are controlled to be positioned adjacent to each other ina linear manner on the supporting rails. “Linear manner” may in thiscontext mean that the vehicles are positioned, or are moving, along aline which coincides with or is parallel with the supporting rails onthe grid structure. This leads to a particular efficient operation,since it reduces the time needed from one vehicle's performance of atask at the target location to the next vehicle's performance of a taskat the target location.

Although not illustrated in detail in FIG. 3, the target vehicle controlstep 360 may include the following substeps:

a first substep of controlling the target vehicle to move to the targetlocation; and

a second substep of controlling the target vehicle to pick up the targetbin from the vertical stack at the target location.

The method may be terminated at the terminating step 390, subsequent tothe target vehicle control step 360.

Advantageously, the method may include a further step, performedsubsequent to the target vehicle control step 360 and prior to theterminating step 390, the further step including controlling the atleast one non-target vehicle to return and unload its bin to the targetlocation. In case of a plurality of non-target vehicles holdingnon-target bins, the non-target vehicles are advantageously controlledto return and unload their bins to the target location in oppositeorder, compared to the order in which the non-target vehicles picked uptheir respective non-target bins in the repeated sequence of steps 320,330, 340 and 350.

A more detailed example of how the method can be practiced has also beenpresented below with reference to FIGS. 5-9.

FIG. 4 is a schematic block diagram illustrating a storage system, inparticular including communication elements that are suitable in asystem and method as disclosed herein.

The system 400 includes a storage structure 430 which may be similar tothe storage structure 3 referred to in the section Background of theinvention above.

Hence, the storage system 400 includes a three-dimensional storage gridcontaining a plurality of bins stacked in vertical stacks; supportingrails on the grid structure; and a plurality of vehicles, controllablyarranged to move on the supporting rails.

To make the vehicles controllable, a control device 420 is provided. Inorder to provide communication between the vehicles and the controldevice, the system may include a communication device 410, whichfacilitates communication, preferably wireless communication, such asdigital RF communication, between the control device 420 and eachvehicle. The communication device 410 is further communicativelyconnected to the control device 420, either by wire or wirelesscommunication means. The communication device 410 and the control device420 may be separate units or combined into one unit.

Each vehicle is arranged to move on supporting rails and to receive astorage bin from a storage column within the bin storing grid. Forinstance, each, several or all the vehicles may be of the type asillustrated in FIG. 2 and referred to in the section Background of theinvention above. Alternatively, each, several or all the vehicles may beof a type that includes a vehicle body and a cavity arranged centrallywithin the vehicle body, the cavity being arranged to receive and hold astorage bin.

Each vehicle is provided with rolling means, such as wheels. Typically,the vehicle includes a first and a second set of wheels, each setincluding four wheels, and the first set of wheels being arrangedperpendicularly to the second set of wheels. Such an arrangement mayenable the vehicle to move along supporting rails extending in a firstdirection on the grid structure and along supporting rails extending ina second direction on the grid stricture. The first and seconddirections of the supporting rails are also advantageouslyperpendicular. The vehicle may include a controllable mechanism forselectively displacing, from the rails, either the first or second setof wheels. This arrangement enables controllable, quick change ofvehicle direction between the first direction and the second direction.

At least one wheel in a set of wheels is driven by a motor, typically anelectric motor. The displacing mechanism may also be actuatedelectrically. The motor and other energy-consuming equipment on thevehicle is typically powered by a rechargeable battery onboard thevehicle.

To make the vehicles controllably arranged to move as desired on thesupporting rails, each vehicle is advantageously provided with localcontrol/processing means which provides the detailed control of therotation of wheels and the controllable displacing mechanism. Sensorsmay also be arranged in the vehicles and connected to thecontrol/processing means on the vehicle, and signals provided by suchsensors may be used in the local control provided on the vehicle. Suchsensors may, i.a, include proximity and position sensors, e.g. opticalsensors.

Each vehicle further includes a controllable mechanism which enables thevehicle to pick up (or load) a bin from a location at the storage grid,and/or to drop off (or unload) a bin to a location at the storage grid.

The control/processing means on the vehicle provides local control ofi.a. the speed and rolling direction of wheels, and of theloading/unloading mechanism. This may be achieved by configuringsuitable software in a memory included in the vehicle'scontrol/processing means, enabling the control/processing means tocontrol i.a. the rotational direction, speed and acceleration of thevehicle's wheel(s).

The control/processing means on the vehicle may also be configured toreceive instructions or requests from a remote control device, theinstructions or requests being on a higher conceptual level than thedetailed control of direction, speed, etc. For instance, thecontrol/processing means on the vehicle may be enabled to receive arequest for moving the vehicle to a particular position on the storagegrid, or to pick up a bin from the grid at a particular position on thestorage grid, and to control the vehicle to move and act accordingly.

Further with reference to FIG. 4, the storage system 400 also includes acontrol device 420, which may be a computer device, including, i.e., aprocessing device and a memory which includes a computer programconfigured to be executed on the processing device.

The control device 420 is configured to transmit instructions orrequests to each vehicle via the communication device 410. The controldevice 420 holds information about each vehicle's position, load status,etc. in an associated memory.

Hence, the control device 420 is enabled to transmit instructions orrequest on a higher conceptual level to each vehicle, as alreadydescribed above.

The control device 420 may be configured to identify a “target vehicle”,i.e., a vehicle that is intended to hold a particular bin to be fetchedin the storage grid, denoted the “target bin”. To this end, the controldevice 420 may for instance be configured to select a vehicle that iscurrently unoccupied and determine that vehicle to be a “targetvehicle”.

The control device 420 may also be configured to identify at least“non-target vehicle”, i.e. a vehicle that is intended to be used as anintermediate storage for bins that must be removed in order to obtainthe target bin in the storage grid. To this end, the control device 420may be configured to select a vehicle that is currently unoccupied anddetermine that vehicle to be a “non-target vehicle”. The control device420 may also be configured to control the non-target vehicles and thetarget vehicle to place themselves in a set of positions wherein theyare prepared to perform an operation of fetching the target bin. Inparticular, the control device 420 may be configured to control thenon-target vehicles and the target vehicle to place themselves adjacentto each other on the supporting rails in a linear manner, and in such away that a non-target vehicle is located vertically above the targetbin.

Alternatively, the process of identifying a “target vehicle” and“non-target vehicles” may be distributed to the control/processing meansin the vehicles, since each vehicle holds status information whichindicates if the vehicle is currently busy, i.e., unavailable forservice. or unoccupied, i.e., available for service.

By these or similar provisions, the control device 420 is configured tofetch a target bin stored in the storage system 400 by controlling atleast one non-target vehicle to operate as intermediate storage for atleast one bin located vertically above the target bin; controlling atarget vehicle to pick up the target bin, and controlling the at leastone non-target vehicle and the target vehicle to be positioned adjacentto each other in a linear manner on the supporting rails.

In a particular aspect of the storage system 400, the control device 420is configured to controlling the at least one non-target vehicle tooperate as intermediate storage for at least one bin located verticallyabove the target bin. More specifically, the control device 420 may beconfigured to control a non-target vehicle to move to a target locationabove the target bin; control the non-target vehicle to pick up a binfrom the vertical stack at the target location; to control thenon-target vehicle to a neighbour location; and to repeat the abovecontrolling steps until the target bin has become the upper bin in thevertical stack at the target location.

Advantageously, in this aspect, the control device may also beconfigured to control the target vehicle to pick up the target bin by:controlling the target vehicle to move to the target location; andcontrolling the target vehicle to pick up the target bin from thevertical stack at the target location.

In any of the above aspects, the control device 420 may be furtherconfigured to control the non-target vehicles to return and unload theirbins to the target location.

In this case the control device may also be further configured tocontrol the non-target vehicles to return and unload their bins to thetarget location in opposite order.

The control device 420 may include memory that holds and updates datarepresenting various information about the storage system. Suchinformation may include current position and identification of storagebins stored in the storage structure, as well as current position andidentification of vehicles that move or are stationary disposed on thesupporting rails on the grid structure.

FIGS. 5-9 are schematic diagrams illustrating an exemplary operation ofthe method and system.

FIG. 5 illustrates an initiate situation wherein a number of vehicles(four shown) are available on the top of the storage grid structure. Thevehicles are arranged to move on supporting rails on the top of thestorage grid structure. A plurality of bins (ten shown) are stacked in avertical stack in the three-dimensional storage grid structure. Of thesebins, the bin denoted by number “5” is determined to be a target bin.

FIG. 5 also illustrates that a non-target vehicle (the rightmost vehiclein FIG. 5) has been controlled to move to a target location above thetarget bin.

FIG. 6 illustrates that the non-target vehicle (the rightmost vehicle inFIG. 6), located above the target bin, has been controlled to pick up abin (denoted by number “1”).

FIG. 7 illustrates that the non-target vehicle that holds the bindenoted by number “1” has been controlled to rest at a neighbourposition on the storage grid. The controlling steps have then beenrepeated three times. Hence, further 3 non-target vehicles have beencontrolled to move to the target location above the target bin and beencontrolled to pick up a bin from the vertical stack at the targetlocation, and been controlled to rest at a neighbour location. In thesituation illustrated at FIG. 7, the target bin (denoted “5”) has becomethe upper bin in the vertical stack at the target location. Hence, therepeating of controlling steps is terminated.

FIG. 8 illustrates that the target vehicle (the leftmost vehicle in FIG.8) has been controlled to move to the target location and beencontrolled to pick up the target bin (denoted “5”). Consequently, thetarget vehicle has fetched the target bin and may carry the target binto another location, such as a bin lift device which may cause thetarget bin to be conveyed to a delivery station.

FIG. 9 illustrates that the non-target vehicles have returned andunloaded their bins to the target location. Since the non-targetvehicles return and unload their bins to the target location in oppositeorder, the result will be that the non-target bins appear in the gridstructure in their original order. Only the target bin (denoted “5”) ismissing.

As can be noted from any one of FIGS. 6, 7, 8 and 9, all the non-targetvehicles and the target vehicle are positioned adjacent to each other ina linear manner on the supporting rails at any time during the processof retrieving the target bin. This leads to a particular efficientoperation, since it reduces the time needed from one vehicle'sperformance of a task at the target location to the next vehicle'sperformance of a task at the target location.

In the above detailed description, various aspects of the method andsystem have been described with reference to the illustrated exemplaryembodiment. Various modifications and variations of the exemplaryembodiment, as well as other embodiments of the method and system, areconsidered to lie within the scope of the present invention as definedin the claims.

The invention claimed is:
 1. A method for fetching a target bin storedin a storage system, wherein the storage system includes, athree-dimensional storage grid containing a plurality of bins stacked invertical stacks, further comprising supporting rails on the gridstructure, a plurality of vehicles, controllably arranged to moveindividually on the supporting rails, the method comprising: controllingat least one non-target vehicle to operate as intermediate storage for abin located vertically above the target bin; controlling a targetvehicle to pick up the target bin, and controlling the at least onenon-target vehicle and the target vehicle to be positioned adjacent toeach other in a linear manner on the supporting rails, wherein the stepof controlling at least one non-target vehicle to operate asintermediate storage for a bin located vertically above the target binfurther comprises: controlling a non-target vehicle to move to a targetlocation above the target bin; controlling the non-target vehicle topick up a bin from the vertical stack at the target location;controlling the non-target vehicle to rest at a neighbor location; andrepeating the controlling steps until the target bin has become theupper bin in the vertical stack at the target location.
 2. The methodaccording to claim 1, wherein the step of controlling the target vehicleto pick up the target bin comprises: controlling the target vehicle tomove to the target location; and controlling the target vehicle to pickup the target bin from the vertical stack at the target location.
 3. Themethod according to claim 1, further comprising controlling the at leastone non-target vehicle to return and unload its bin to the targetlocation.
 4. The method according to claim 1, wherein each non-targetvehicle is arranged to operate as intermediate storage for a single bin.5. A storage system, comprising, a three-dimensional storage gridcontaining a plurality of bins stacked in vertical stacks and furthercomprising supporting rails on the grid structure; a plurality ofvehicles, controllably arranged to move on the supporting rails, and acontrol device, wherein the control device is configured to enablefetching of a target bin stored in the storage system by controlling atleast one non-target vehicle to operate as intermediate storage for abin located vertically above the target bin; controlling a targetvehicle to pick up the target bin; and controlling the at least onenon-target vehicle and the target vehicle to be positioned adjacent toeach other in a linear manner on the supporting rails, wherein thecontrol device is configured to control the at least one non-targetvehicle to operate as intermediate storage for a bin located verticallyabove the target bin by: controlling a non-target vehicle to move to atarget location above the target bin; controlling the non-target vehicleto pick up a bin from the vertical stack at the target location;controlling the non-target vehicle to rest at a neighbour location; andrepeating the controlling steps until the target bin has become theupper bin in the vertical stack at the target location.
 6. The storagesystem according to claim 5, wherein the control device is configured tocontrol the target vehicle to pick up the target bin by: controlling thetarget vehicle to move to the target location; and controlling thetarget vehicle to pick up the target bin from the vertical stack at thetarget location.
 7. The storage system according to claim 5, wherein thecontrol device is further configured to control the at least onenon-target vehicle to return and unload its bin to the target location.8. The storage system according to claim 5, wherein each non-targetvehicle is arranged to operate as intermediate storage for a single bin.